The present invention relates to a three-piece solid golf ball. More particularly, it relates to a three-piece solid golf ball having long flight distance when hit by using from a middle iron club to a driver, and excellent controllability by accomplishing high spin amount when hit by a short iron club and the like, while maintaining good shot feel.
Solid golf balls, which have good rebound characteristics and small spin amount, are generally approved of or employed by most of general amateur golfers, who regard flight distance as most important characteristics of golf ball. On the other hand, professional golfers and high level golfers regard controllability as most important, followed by soft and good shot feel, and flight performance. Therefore they have mainly employed thread wound golf balls, because they regard controllability as most important and the golf ball has soft and good shot feel. However, it is problem that the thread wound golf ball has a structure, which is easy to apply spin, and it has high spin amount when hit by every golf club, which degrades the flight performance. In order to solve the problem, many solid golf balls, of which the shot feel and flight performance are improved while maintaining good controllability, have been proposed (Japanese Patent Kokai Publication Nos. 332247/1996, 313643/1997, 151320/1999 and the like).
In Japanese Patent Kokai Publications No. 332247/1996, a three-piece solid golf ball which comprises a two-layer structured core composed of an inner core and outer core, and a cover is described. The inner core has a diameter of 25 to 37 mm, has a center hardness in JIS-C hardness of 60 to 85 and has a hardness difference from the center of the inner core to the surface of the inner core is within the range of not more than 4, the outer core has a surface hardness in JIS-C hardness of 75 to 90, and the cover has a flexural modulus of 1,200 to 3,600 kg/cm2.
In Japanese Patent Kokai Publications No. 313643/1997, a three-piece solid golf ball, of which an intermediate layer formed from thermoplastic resin is placed between a core and a cover is described. The core has a center hardness in JIS-C hardness of not more than 75 and has a surface hardness in JIS-C hardness of not more than 85, the surface hardness is higher than the center hardness by 5 to 25, a hardness of the intermediate layer is higher than the surface hardness of the core by less than 10, and a hardness of the cover is higher than the hardness of the intermediate layer.
In Japanese Patent Kokai Publication No. 151320/1999, a three-piece solid golf ball which comprises a two-layer structured core composed of an inner core and outer core, and a cover is described. The inner core has a diameter of 15 to 22 mm and Shore D hardness of 40 to 70, the outer core has a JIS-C hardness of 40 to 75, the inner core and outer core are formed from rubber composition, and the cover has a thickness of 0.5 to 3 mm;
However, in the golf balls described above, spin amount is large when hit by using from a driver to a middle iron club, where long flight distance is still required, and the flight distance is reduced. In addition, if the flight distance will be improved, shot feel is hard or heavy, and poor. Therefore, a golf ball having sufficient performances has not been obtained.
A main object of the present invention is to provide a three-piece solid golf ball, of which flight distance is long when hit by using from a middle iron club to a driver; spin amount is large when hit by a short iron shot and the like, and the controllability is excellent; while maintaining good shot feel at the time of hitting as good as thread golf balls.
According to the present invention, the object described above has been accomplished by providing a three-piece solid golf ball comprising a core having a two-layered structure, which is composed of a center and an intermediate layer, and a cover, and adjusting a diameter and central point hardness of the center, a surface hardness of the intermediate layer and a hardness of the cover to specified ranges, thereby providing a three-piece solid golf ball, of which flight distance is long when hit by using from a middle iron club to a driver; spin amount is large when hit by a short iron shot and the like, and the controllability is excellent; while maintaining good shot feel at the time of hitting as good as thread golf balls.
This object as well as other objects and advantages of the present invention will become apparent to those skilled in the art from the following description with reference to the accompanying drawings.